Physical quantity sensor and manufacturing method therefor

ABSTRACT

A physical quantity sensor includes a pair of physical quantity sensor chips that are inclined with respect to the bottom of an exterior mold package whose side surfaces are each inclined in a thickness direction by an angle ranging from 0° to 5° and are formed in proximity to the outer ends of the physical quantity sensor chips. It is possible to realize the inclination of stages without using molds, wherein absorption devices are used to absorb prescribed portions related to stages, which rotate about axial lines and are thus inclined with respect to a prescribed base. In manufacturing, a thin metal plate having a plurality of lead frames is placed on a base delimited by a clamp; then, intersecting points of intermediate portions formed between the lead frames are subjected to pressing so as to realize the inclination of stages.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of application Ser. No. 11/244,194,filed Oct. 6, 2005, entitled PHYSICAL QUANTITY SENSOR AND MANUFACTURINGMETHOD THEREFOR, the entire disclosure of which is incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to physical quantity sensors that measurebearings and directions regarding physical quantities such as magnetismand gravitation. The present invention also relates to manufacturingmethods of physical quantity sensors.

This application claims priorities on Japanese Patent Applications Nos.2004-296371, 2005-45299, 2005-89629, and 2005-94388, the contents ofwhich are incorporated herein by reference.

2. Description of the Related Art

Recently, sensing technologies regarding measurement of bearings anddirections in a three-dimensional space have been developed to providevarious types of physical quantity sensors, such as magnetic sensors andacceleration sensors, which detect physical quantities such as magnetismand acceleration. For example, Japanese Unexamined Patent ApplicationPublication No. 2004-128473 discloses an example of a magnetic sensorusing a specially-designed lead frame.

It is known that physical quantity sensors are each equipped withphysical quantity sensor chips (or magnetic sensor chips) which aremutually inclined with respect to each other. Due to the mutualinclination of paired physical quantity sensor chips, it is possible todetect magnetic factors lying in three directions (e.g., X-axis andY-axis directions that are perpendicular to each other on the plane, aswell as a Z-axis direction perpendicular to the X-axis and Y-axisdirections); hence, it is possible to measure the direction ofgeomagnetism based on detected values as vectors existing in athree-dimensional space. Thus, it is possible to reduce the overallthickness of physical quantity sensors.

In addition to the aforementioned advantage in which physical quantitysensors each having mutually inclined physical quantity sensor chips canbe reduced in the overall thickness thereof, it is possible to providethe following advantages.

For example, Japanese Unexamined Patent Application Publication No.H09-292408 teaches an example of an acceleration sensor, i.e., aphysical quantity sensor of a one-sided beam structure in which aphysical quantity sensor chip (i.e., an acceleration sensor chip) isinclined in advance with respect to a substrate therefor.

In the above, even when a sensor package is mounted on the surface ofthe substrate, it is possible to maintain a sensitivity in a prescribedaxial direction in response to the inclination direction of the physicalquantity sensor chip; and it is possible to reduce sensitivities inother axial directions including directions lying along the surface ofthe substrate. As a result, it is possible to maintain prescribedproduct characteristics in shipment.

Specifically, FIG. 17 shows a known structure of a physical quantitysensor 100 having an exterior mold portion 101 for fixing a pair ofmagnetic sensor chips 103, which are inclined with respect to eachother, onto a bottom 102. The exterior mold portion 101 is molded usinga resin. For this reason, side surfaces 105 of the exterior mold portion101 generally have slopes that are each inclined in a thicknessdirection H by predetermined angles.

The aforementioned physical quantity sensor 100 can be adapted to aportable terminal device such as a portable telephone (or a cellularphone) having a navigation function, for example. Due to the recenttendency in which portable terminal devices have been reduced indimensions, there may be a demand for the aforementioned physicalquantity sensor 100 to be further reduced in dimensions. In order torealize compactness of the physical quantity sensor 100, it may benecessary to reduce dimensions G lying in a length direction W of thebottom 102 to as small as possible.

However, due to the slopes having prescribed angles adapted to the sidesurfaces 105 of the physical quantity sensor 100, both ends of thebottom 102 lying in the length direction W must be greatly projectedoutwardly beyond terminal ends 104 of the physical quantity sensor chips103. This causes a bottleneck making it difficult further reducedimensions of the physical quantity sensor 100.

Recently, portable terminal devices such as portable telephones (orcellular phones) have been equipped with GPS (Global Positioning System)functions for displaying users' present locations on earth. In addition,portable terminal devices can be further developed to have functions forprecisely measuring geomagnetism and acceleration in addition to GPSfunctions; hence, it is possible for portable terminal devices held byusers to measure bearings and directions thereof in a three-dimensionalspace as well as moving directions thereof.

In order to realize the aforementioned functions in portable terminaldevices, it is necessary to incorporate physical quantity sensors suchas magnetic sensors and acceleration sensors. In order to measurebearings and acceleration in a three-dimensional space, it is necessarythat stages facilitating physical quantity sensor chips be inclined withrespect to prescribed bases.

For example, one type of known magnetic sensor presently sold on themarket is designed such that stages facilitating physical quantitysensor chips are not necessarily inclined with respect to prescribedbases. In this type of physical quantity sensor, there are provided afirst magnetic sensor chip sensitive to magnetic factors lying in twodirections (i.e., X-axis and Y-axis directions perpendicular to eachother) of an external magnetic field and a second magnetic sensor chipsensitive to a magnetic factor lying in another direction (i.e., aZ-axis direction), wherein both the first and second magnetic sensorchips are mounted on the surface of a substrate.

The aforementioned magnetic sensor measures geomagnetic factors asvectors in a three-dimensional space based on magnetic factors detectedby a pair of the first and second magnetic sensor chips.

However, the aforementioned magnetic sensor is basically designed suchthat the second magnetic sensor chip vertically stands on the surface ofthe substrate; hence, it is disadvantageous in that the thicknessthereof (lying in the Z-axis direction) must be increased. In order tominimize the thickness, it is necessary to use physical quantity sensorsin which stages facilitating physical quantity sensor chips are inclinedwith respect to prescribed bases. Examples have been disclosed invarious papers such as Japanese Unexamined Patent ApplicationPublications Nos. 2004-128473 and H09-292408, which have already beendiscussed above. In addition, Japanese Unexamined Patent ApplicationPublication No. 2002-156204 discloses a magnetic sensor and an anglesensor having reduced dimensions.

As described above, a plurality of physical quantity sensor chips aremutually inclined with respect to each other inside of the physicalquantity sensor, whereby it is possible to detect magnetic factors inthree directions (i.e., X-axis, Y-axis, and Z-axis directions); hence,it is possible to measure the geomagnetic direction as vectors in athree-dimensional space on the basis of detection results. Due to themutual inclination of physical quantity sensor chips, it is possible toreduce the height in the Z-axis direction; in other words, it ispossible to minimize the thickness of the magnetic sensor.

In the above, it is required that an angle formed between two stagesfacilitating two magnetic sensor chips ranges from 0° to 90°. It ispreferable that the angle be greater than 20°; and it is furtherpreferable that the angle be greater than 30°. This is because a largerangle may improve the sensitivity lying in the Z-axis direction, whichis well isolated from the X-axis and Y-axis directions.

As described above, physical quantity sensors in which physical quantitysensor chips are mutually inclined with respect to each other areadvantageous in that the thickness thereof can be minimized so as tocope with downsizing of electronic devices, wherein they have variousadvantages due to the mutual inclination of physical quantity sensorchips and thus will contribute to mainstream technologies in the future.

An example of a physical quantity sensor in which physical quantitysensor chips are mutually inclined with respect to each other will bedescribed with reference to FIG. 18. Physical quantity sensor chips aremounted on stages of a lead frame encapsulated in a resin mold package,wherein they are supported in a mutually inclined state by projectionswhich project downwardly from stages towards the bottom of the resinmold package.

In manufacturing, a thin metal plate is subjected to press working so asto form the lead frame having the stages; then, projections are formedto project from the opposite ends of the lower surfaces (or back sides)of the stages. The lead frame is held and fixed in a pair of metal moldsrealizing a cavity of a prescribed shape therebetween, wherein the tipends of the projections are pressed by the interior wall of the lowermetal mold, so that the stages are rotated about axial lines relative tointerconnection portions which are interconnected to the bases of thestages, and are thus appropriately bent; hence, the lead frame includingthe stages and projections is processed as shown in FIG. 18. Thereafter,a resin is introduced into the cavity of the metal molds. Thus, theopposite ends of the stages are respectively directed towards the uppersurface of the resin mold package, whereby the stages are supported bythe projections in a mutually inclined state.

In the aforementioned manufacturing method, the projections aresubjected to pressing using a pair of metal molds, which are thereforelikely to be damaged. In addition, it may require a troublesome work toprecisely incline the stages by pressing.

As the stages of the lead frame are subjected to inclination using theupper and lower molds by way of the projections, which project from thestages, the physical quantity sensor has a drawback in that the overallsize of the package encapsulating the lead frame and physical quantitysensor chips is increased due to the provision of the projections.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a physical quantitysensor and a manufacturing method therefor, in which the physicalquantity sensor is downsized with a simple structure.

It is another object of the present invention to provide a manufacturingmethod for a physical quantity sensor without using metal molds, whichare used to hold a lead frame therebetween. Even though metal molds areused in manufacturing, the present invention makes it possible toimprove the durability of metal molds. In addition, the presentinvention makes it possible to quickly and easily manufacture physicalquantity sensors.

It is a further object of the present invention to provide amanufacturing method for a physical quantity sensor, which can bereduced in size and which can be smoothly produced with a reduced cost.

In a first aspect of the present invention, a physical quantity sensoris constituted using a pair of physical quantity sensor chipsencapsulated in an exterior mold package, which is molded using a resin,wherein the physical quantity sensor chips are inclined with respect tothe bottom of the exterior mold package, and wherein the side surfacesof the exterior mold package are each inclined inwardly in a thicknessdirection by an angle, which ranges from 0° to 5°, and are formed inproximity to outer ends of the physical quantity sensor chips, which arearranged opposite to each other.

By increasing the angle with regard to the side surfaces of the exteriormold package that are broadened outwardly, it is possible to reduce thelength of the bottom of the exterior mold package, whereby it ispossible to reduce the overall area of the bottom of the exterior moldpackage. This realizes downsizing of the physical quantity sensor.

In the above, a plurality of leads are formed and are electricallyconnected to the physical quantity sensor chips in such a way that theleads partially overlap with the physical quantity sensor chips in thethickness direction. This contributes to a further reduction of thelength of the bottom of the exterior mold package; hence, it is possibleto realize downsizing of the physical quantity sensor.

In addition, the lead has an inclination portion, which is inclined withrespect to the bottom of the exterior mold package and on which thephysical quantity sensor chips are arranged. This makes it easy for thephysical quantity sensor chip to be inclined without coming in contactwith the leads.

In a manufacturing method for a physical quantity sensor in which a pairof physical quantity sensor chips are incorporated into an exterior moldpackage, which is molded using a resin, and are each inclined withrespect to the bottom of the exterior mold package, wherein a bondingstep is performed such that the physical quantity sensor chips arebonded onto stages of a lead frame, which is formed by processing a thinmetal plate, a connection step is performed such that an electricconnection is established between the lead frame and the physicalquantity sensor chips; a fixing step is performed such that the leadframe equipped with the physical quantity sensor chips is fixed into acavity of a metal mold; and a molding step is performed such that aresin is injected into the cavity of the metal mold holding the leadframe and the physical quantity sensor chips, thus forming the exteriormold package, wherein side surfaces of the exterior mold package areeach inclined in a thickness direction by an angle, which ranges from 0°to 5°, and are formed in proximity to outer ends of the physicalquantity sensor chips.

In the above, it is possible to introduce a dicing step in which bysetting the angle to zero, the lead frame and the exterior mold packageare subjected to dicing so that the side surfaces of the exterior moldpackage are formed in proximity to the outer ends of the physicalquantity sensor chips. This eliminates the necessity of arrangingextraction slopes in the side surfaces of the exterior mold package;hence, it is possible to realize downsizing of the physical quantitysensor with a simple structure.

In a second aspect of the present invention, there is provided amanufacturing method for a physical quantity sensor using a lead framehaving a plurality of stages, a frame portion having a plurality ofleads that are formed to encompass the stages, and a plurality ofinterconnection portions for interconnecting prescribed ends of thestages to the frame portion, wherein a bonding step is performed suchthat a plurality of physical quantity sensor chips are bonded onto thestages of the lead frame; a connection step is performed such that theleads are electrically connected to the physical quantity sensor chips;an installation step is performed such that the lead frame is placedonto a planar surface of a base; and an inclination step is performedsuch that prescribed portions related to the stages of the lead frameare subjected to absorption onto the base, wherein due to absorption,the stages mutually rotate about axial lines while the interconnectionportions are being bent, so that the stages are inclined with respect tothe frame portion. This removes metal molds used to hold the lead frame,wherein the stages can be easily inclined.

In the above, a plurality of lead frames are formed in a single sheet ofa thin metal plate. Herein, the installation step is performed such thatthe periphery of the thin metal plate having the frame portionencompassing a plurality of lead frames are fixed by means of a clampthat vertically stands on the planar plane of the base; a molding stepis performed such that a resin is introduced into a space holding thethin metal plate, which is defined by the planar plane and the clamp, soas to simultaneously mold exterior mold packages respectivelyencapsulating the lead frames; and a dicing step is performed such thatthe frame portion is subjected to dicing so as to isolate individualunits of the exterior mold packages. This eliminates the necessity ofusing extraction slopes in the exterior mold packages; hence, it ispossible to reduce the bottom area of the exterior resin package; thus,it is possible to realize downsizing of a magnetic sensor.

In addition, a plurality of projections are formed so as to projectdownwardly from the stages, so that due to absorption of the prescribedportions, which match a lower surface of the frame portion in proximityto the stages, the projections are subjected to pressing so thatprescribed ends of the stages are pressed upwardly. This makes it easyfor the stages to rotate about axial lines passing through theinterconnection portions, so that the prescribed ends of the stages arelifted up; thus, the stages are inclined with respect to the frameportion.

Alternatively, the stages are lifted upwards from the frame portion withprescribed offset values, so that due to absorption of the prescribedportions, prescribed ends of the stages are lowered downwards.

Alternatively, a plurality of inclination portions are each extendedupwardly from the stages in a slanted manner, so that the inclinationportions are subjected to absorption and are lowered so as to lift upprescribed ends of the stages.

As described above, it is possible to incline the stages with respect tothe frame portion with ease without using metal molds to hold the leadframe, whereby it is possible to manufacture a magnetic sensor in ashort period of time. Even though the upper and lower metal molds areused to hold the lead frame, they do not necessarily press theprescribed portions of the lead frame; hence, it is possible to preventthe metal molds from being damaged; thus, it is possible to improve thedurability of the metal molds.

In a third aspect of the present invention, there is provided amanufacturing method for a physical quantity sensor using a lead framethat includes a plurality of stages for mounting physical quantitysensor chips thereon, a frame portion having a plurality of leadsencompassing the stages, and a plurality of interconnection portions forinterconnecting prescribed ends of the stages to the frame portion,wherein a frame forming step is performed such that a plurality of leadframes are formed in a thin metal plate; a bonding step is performedsuch that the physical quantity sensor chips are bonded onto the stagesin each of the lead frames; a connection step is performed such that theleads are electrically connected to the physical quantity sensor chips;an installation-fixation step is performed such that the thin metalplate is placed on a planar surface of a base, on which the periphery ofthe thin metal plate is clamped using a clamp, which vertically standson the planar surface of the base; an inclination step is performed suchthat prescribed portions of the thin metal plate formed in proximity tothe stages are subjected to pressing in a direction perpendicular to theplanar surface so as to incline the stages with respect to the frameportion while the interconnection portions are being bent about axiallines; a molding step is performed such that a resin is introduced intoa space defined by the clamp and the planar surface of the base so as tomold a package encapsulating the lead frame in which the stages aremutually inclined with respect to each other; and a dicing step isperformed such that the frame portion and the package are subjected todicing. This realizes the inclination of the stages without usingprojections, which project from the stages.

In the above, pressing pins are used to press the prescribed portionsformed in proximity to the stages in the direction perpendicular to theplanar surface so as to incline the stages with respect to the frameportion. This makes it possible to reliably incline the stages with asimple structure.

In addition, the prescribed portions formed in proximity to the stagesare subjected to absorption in the direction towards the planar surface,wherein projections projecting from the stages are subjected to pressingby the planar plane due to absorption, so that the opposite ends of thestages are moved oppositely to the planar plane, thus inclining thestages with respect to each other. When the projections are pressed bythe planar plane, the stages rotate about axial lines relatively to theinterconnection portions; hence, the opposite ends of the stages aremoved oppositely to the planar plane, thus realizing the inclination ofthe stages.

Alternatively, the prescribed portions formed in proximity to the stagesare subjected to absorption in the direction towards the planar plane,wherein the stages are initially positioned apart from the planar planeof the base with prescribed offset values, so that the opposite ends ofthe stages are moved towards the planar plane due to absorption, thusinclining the stages with respect to each other.

Alternatively, the prescribed portions formed in proximity to the stagesare subjected to absorption in the direction towards the planar plane,wherein inclination portions extending from the stages are inclined dueto absorption, thus inclining the stages with respect to each other.

As described above, the stages can be easily inclined with respect toeach other without using the projections. This makes it possible todownsize the physical quantity sensor; hence, it is possible to speedilyproduce the physical quantity sensor with a reduced cost.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, aspects, and embodiments of the presentinvention will be described in more detail with reference to thefollowing drawings, in which:

FIG. 1 is a plan view showing the overall structure of a magnetic sensorthat is a physical quantity sensor in accordance with a first embodimentof the present invention;

FIG. 2 is a cross-sectional view showing essential parts of the magneticsenor;

FIG. 3 is an enlarged cross-sectional view showing an inclination of amagnetic sensor chip encapsulated in an exterior mold package;

FIG. 4 is a plan view showing a lead frame for use in the magneticsensor shown in FIG. 1;

FIG. 5 is a side view showing essential parts of the lead frame;

FIG. 6 is a cross-sectional view showing the lead frame held betweenmetal molds;

FIG. 7 is a cross-sectional view showing the lead frame that issubjected to pressing in a cavity between the metal molds;

FIG. 8 is a plan view showing the structure of a physical quantitysensor in accordance with a first modification of the first embodiment;

FIG. 9 is a perspective view showing stages and associated parts thatare inclined in the physical quantity sensor according to the firstmodification;

FIG. 10 is an enlarged side view showing a tip end of a projection thatis modified in accordance with a second modification of the firstembodiment;

FIG. 11 is a cross-sectional view for explaining the formation of anR-shape portion at the tip end of the projection shown in FIG. 10;

FIG. 12 is a side view showing that the tip end of a projection forinclining a stage is extended in accordance with a third modification ofthe first embodiment;

FIG. 13 is a cross-sectional view for explaining the formation of anextended portion that extends from the tip end of the projection shownin FIG. 12;

FIG. 14 is a side view showing that the extended portion is reduced inthickness compared with other portions of the projection shown in FIG.12;

FIG. 15 is a perspective view showing a lead frame realizing a pluralityof magnetic sensors in accordance with a fourth modification of thefirst embodiment;

FIG. 16 is a perspective view showing a lead frame realizing a pluralityof magnetic sensors in accordance with a fifth modification of the firstembodiment;

FIG. 17 is a cross-sectional view showing a typical structure of aconventionally-known magnetic sensor having two chips inclined withrespect to each other;

FIG. 18 is a traverse cross-sectional view showing the structure of aconventionally-known physical quantity sensor;

FIG. 19 is a cross-sectional view showing essential parts of a magneticsensor that is produced in accordance with a second embodiment of thepresent invention;

FIG. 20 is a plan view showing a lead frame having stages, on whichmagnetic sensor chips are mounted, for use in the magnetic sensor shownin FIG. 19;

FIG. 21 is a plan view showing a thin metal plate on which a pluralityof lead frames each shown in FIG. 20 are formed;

FIG. 22 is a cross-sectional view showing that the thin metal plate ofFIG. 21 is placed on a base;

FIG. 23 is a cross-sectional view showing that the thin metal plate ofFIG. 21 is subjected to clamping on the base;

FIG. 24 is a cross-sectional view showing that selected portions of thethin metal plate shown in FIG. 23 are subjected to absorption so as toincline stages on the base;

FIG. 25 is a cross-sectional view showing that a resin is introducedinto a space holding the thin metal plate shown in FIG. 24;

FIG. 26 is a plan view showing a modification of the lead frame of FIG.20 in which projections are replaced with slits;

FIG. 27 is a cross-sectional view showing essential parts of the leadframe shown in FIG. 26, which is placed between upper and lower molds soas to incline stages;

FIG. 28 is a side view showing essential parts of a lead frame includedin a thin metal plate in accordance with a first modification of thesecond embodiment;

FIG. 29 is a side view showing that due to absorption caused by anabsorption device, stages of the lead frame shown in FIG. 28 areinclined with respect to a base;

FIG. 30 is a side view showing essential parts of a lead frame inaccordance with a second modification of the second embodiment;

FIG. 31 is a side view showing that due to absorption caused by anabsorption device, stages of the lead frame shown in FIG. 30 areinclined with respect to a base;

FIG. 32 is a plan view showing the structure of a lead frame havinginclination portions in accordance with a third modification of thesecond embodiment;

FIG. 33 is a side view showing that inclination portions of the leadframe are subjected to absorption by way of absorption devices viaabsorption holes on a base;

FIG. 34 is a side view showing that due to absorption of the inclinationportions, stages of the lead frame shown in FIG. 33 are lifted up andthus inclined with respect to the base;

FIG. 35 is a side view showing essential parts of a lead frame for usein a magnetic sensor, which is manufactured in accordance with a thirdembodiment of the present invention;

FIG. 36 is a cross-sectional view showing essential parts of themagnetic sensor, which is placed on a base associated with a supportframe having pressing pins; and

FIG. 37 is a cross-sectional view showing essential parts of themagnetic sensor, which is clamped on the base and is assembled togetherwith the support frame.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in further detail by way ofexamples with reference to the accompanying drawings.

1. First Embodiment

FIGS. 1 and 2 show a magnetic sensor 1 in accordance with a firstembodiment of the present invention.

The magnetic sensor 1 is designed to measure the magnitude and directionof an external magnetic field, wherein it includes an exterior moldpackage 13, which is molded using a resin, as well as a first magneticsensor chip 2 and a second magnetic sensor chip 3, both of which areincorporated in the exterior mold package 13.

Each of the magnetic sensor chips 2 and 3 has a rectangular plate-likeshape in plan view, wherein they are respectively mounted on a firststage 10 and a second stage 11, which adjoin each other in a lengthdirection W of the magnetic sensor 1. The magnetic sensor chips 2 and 3are respectively inclined with respect to a bottom 13 a of the exteriormold package 13. Specifically, the stages 10 and 11 are respectivelyinclined with respect to the bottom 13 a by way of projections 17therefor; hence, inner ends 2 a and 3 a of the magnetic sensor chips 2and 3, which directly face each other, are respectively inclined towardsa top 13 b of the exterior mold package 13, while outer ends 2 b and 3 bof the magnetic sensor chips 2 and 3, which are opposite to the innerends 2 a and 3 a, are respectively inclined towards the bottom 13 a ofthe exterior mold package 13.

The first magnetic sensor chip 2 is sensitive to magnetic factors lyingin two directions of an external magnetic field. That is, it has twosensing directions corresponding to directions A and B, which cross at aright angle along a surface 2 c of the first magnetic sensor chip 2.

The second magnetic sensor chip 3 is sensitive to magnetic factors lyingin two direction of an external magnetic field. That is, it has twosensing direction corresponding to directions C and D, which cross at aright angle along a surface 3 c of the second magnetic sensor chip 3.

In the above, the directions A and C are perpendicular to the lengthdirection W and are opposite each other. In addition, the directions Band D lie along the length direction W and are opposite each other.

In addition, a plane (referred to as an A-B plane) is defined by thedirections A and B along the surface 2 c of the first magnetic sensorchip 2; and a plane (referred to as a C-D plane) is defined by thedirections C and D along the surface 3 c of the second magnetic sensorchip 3. Herein, the A-B plane and the C-D plane cross so as to form anacute angle therebetween; that is, an angle θ₁ between the A-B plane andthe C-D plane is greater than 0° and is less than 90°. Theoretically,the magnetic sensor 1 can measure a bearing of geomagnetism in athree-dimensional space as long as the angle θ₁ is greater than 0°.Actually, it is preferable that the angle θ₁ be greater than 20°; and itis further preferable that the angle θ₁ be greater than 30°.

A plurality of leads 6, which are integrally formed together with thestages 10 and 11, are arranged in proximity to the outer ends 2 b and 3b of the magnetic sensor chips 2 and 3 at both ends of the magneticsensor 1 in its length direction W. The leads 6 are brought into contactwith the outer ends 2 b and 3 b of the magnetic sensor chips 2 and 3;thus, they are electrically connected to the magnetic sensor chips 2 and3. In addition, a plurality of connection leads 7 are formed atprescribed positions lying in directions perpendicular to the lengthdirection W. The connection leads 7 are electrically connected tobonding pads 5 of the magnetic sensor chips 2 and 3 via wires 4. In thepresent embodiment, not all the connection leads 7 are integrally formedtogether with the stages 10 and 11. That is, some connection leads 7 arearranged in proximity to corners relative to the length direction W andare not connected to the bonding pads 5 of the magnetic sensor chips 2and 3. They are brought into contact with the outer ends 2 b and 3 b ofthe magnetic sensor chips 2 and 3.

All the leads 6 and the connection leads 7 are each composed of a metalmaterial such as copper, wherein they are formed in a strip-like shape(or a comb-like shape). Back sides 6 b of bases 6 a of the leads 6 areexposed to the bottom 13 a of the exterior mold package 13. Back sides 7b of bases 7 a of the connection leads 7 are also exposed to the bottom13 a of the exterior mold package 13.

Middle portions 20 of the leads 6 in length directions are subjected tobending so that tip ends 6 c are directed towards the top 13 b of theexterior mold package 13, whereby it is possible to actualizeinclination portions 15, which range from the middle portions 20 to thetip ends 6 c of the leads 6 and which are inclined with respect to thebottom 13 a of the exterior mold package 13. Surfaces 15 a of theinclination portions 15 are arranged in the same planes as the surfaces10 a and 11 a of the stages 10 and 11. The magnetic sensor chips 2 and 3are respectively mounted on the surfaces 10 a and 11 a of the stages 10and 11 supported by the surfaces 15 a of the inclination portions 15.That is, the magnetic sensor chips 2 and 3 and the leads 6 partiallyoverlap each other in a thickness direction H of the magnetic sensor 1.

Side surfaces 13 c, which are formed at both side ends of the exteriormold package 13 in the length direction W, are each inclined by an angleθ₂ that is an inwardly inclined angle and is set to 5° relative to thethickness direction H. In the condition where the magnetic sensor chips2 and 3 are incorporated inside of the exterior mold package 13, theside surfaces 13 c are formed in proximity to outer ends 19 of themagnetic sensor chips 2 and 3 respectively; that is, distances betweenthe side surfaces 13 c and the outer ends of the magnetic sensor chips 2and 3 are shortened. Herein, the side surfaces 13 c are broadenedoutwardly as the angle θ₂ is reduced. In order to reduce the spacesbetween the side surfaces 13 c and the outer ends 19 of the magneticsensor chips 2 and 3, the side surfaces 13 c are broadened in proximityto both ends of the exterior mold package 13.

Specifically, as shown in FIG. 3, the present embodiment is designedsuch that each of the magnetic sensor chips 2 and 3 has a thickness of0.2 mm; an inclination angle between the lower surfaces of the magneticsensor chips 2 and 3 and the bottom 13 a of the exterior mold package 13is set to 15°. In addition, the angle θ₁ between the A-B plane and theC-D plane is set to 30°.

Next, a manufacturing method of the magnetic sensor 1 will be described.

First, a thin metal plate is subjected to press working and/or etchingso as to form a lead frame 22 having a rectangular frame 23 thatencompasses stages 10 and 11 as shown in FIGS. 4 and 5. A plurality ofleads 6 and connection leads 7 are formed to inwardly project from allsides and corners of the rectangular frame 23.

Tip ends 6 c of the leads 6 are interconnected to the stages 10 and 11respectively. Prescribed regions of the leads that range from middleportions 20 to the tip ends 6 c and that partially overlap opposite ends10 b and 11 b of the stages 10 and 11 are formed in the same plane. Inaddition, selected regions of the leads 6 that are extended from themiddle portions 20 to reach the opposite ends 10 b and 11 b of thestages 10 and 11 are subjected to photo-etching and are reduced inthickness compared with other regions. For example, the thickness of theselected regions of the leads 6 is reduced to a half of the thickness ofbases 6 a of the leads 6. The photo-etching is performed prior to pressworking, which is performed on the thin metal plate, in order to preventthe leads 6 and the connection leads 7 as well as back sides 10 c and 11c of the stages 10 and 11 from being exposed in the lower surface of theexterior mold package 13.

Projections 17 are projected downwardly from the back sides 10 c and 11c of the opposite ends 10 b and 11 b of the stages 10 and 11 in aslanted manner. The projections 17 are each formed in a thin rod shape,wherein the projection 17 attached to the first stage 10 is formedoppositely to the projection 17 attached to the second stage 11.

The projections 17 are used to avoid the occurrence of a supply failureof a resin material that is used to form the exterior mold package 13.It is preferable that the distance between the projections 17 isincreased in order to precisely incline the stages 10 and 11 in a stablemanner.

After the preparation of the lead frame 22 having the aforementionedstructure, magnetic sensor chips 2 and 3 are respectively bonded ontothe stages 10 and 11 in a bonding step. The magnetic sensor chips 2 and3 are arranged in prescribed regions that range from the middle portions20 to the tip ends 6 c of the leads 6 to reach the opposite ends 10 band 11 b of the stages 10 and 11, wherein the tip ends 6 c of the leads6 partially overlap the magnetic sensor chips 2 and 3 in the thicknessdirection.

The leads 6 are electrically connected to the bonding pads 5 that areformed on surfaces 2 c and 3 c of the magnetic sensor chips 2 and 3 viathe wires 4 in a connection step.

It is preferable that the wires 4 be composed of a material having abending ability and flexibility because after wiring, when the stages 10and 11 are respectively inclined, mutual variations may occur withrespect to bonding areas between the magnetic sensor chips 2 and 3 andthe wires 4 and with respect to bonding areas between the leads 6 andthe wires 4.

Next, as shown in FIGS. 6 and 7, the lead frame 22 is sandwiched andfixed between metal molds E and F in a fixing step. The metal molds Eand F are used to form the exterior mold package 13 for encapsulatingthe magnetic sensor chips 2 and 3. Side walls E₂ of the lower metal moldE are each inclined by the angle θ₂, which is an inwardly inclined angleand is set to 5° relative to the thickness direction H.

When the metal molds E and F holding the lead frame 22 therebetween aresubjected to pressing, the projections 17 are depressed by an interiorwall F₁ of the upper metal mold F so that the middle portions 20 of theleads 6 are bent towards an interior wall E₁ of the lower metal mold E.That is, the tip ends 6 c of the leads 6 are correspondingly bent aboutthe middle portions 20 together with the stages 10 and 11 in connectionwith the upper mold F. This forms inclination portions 15 with respectto the leads 6. Thus, the magnetic sensor chips 2 and 3 are respectivelyinclined with respect to the interior wall F₁ of the upper mold F.

In the above, the outer ends 19 of the magnetic sensor chips 2 and 3 arearranged in proximity to the side walls E₂ of the lower mold E.

In the aforementioned state, a melted resin is injected into a cavityformed between the metal molds E and F so as to form the exterior moldpackage 13 encapsulating the magnetic sensor chips 2 and 3 in a moldingstep. That is, the magnetic sensor chips 2 and 3 are fixed inside of theexterior mold package 13 while they are inclined with respect to thebottom 13 a of the exterior mold package 13.

Lastly, the lead frame 22 is extracted from the molds E and F; then,prescribed portions of the leads 6 and the connection leads 7, which areprojected outside of the exterior mold package 13, are cut out togetherwith the rectangular frame 23. Thus, it is possible to completelyproduce the magnetic sensor 1 shown in FIG. 1.

Incidentally, the present embodiment does not perform a dicing stepbecause the side surfaces 13 c of the exterior mold package 13 are eachinclined by a small angle of 5°, which is further reduced to zero.

Next, a description will be given with respect to the operation of aphysical quantity sensor (i.e., the magnetic sensor 1) having theaforementioned structure.

The magnetic sensor 1 is installed in a portable terminal device and ismounted on a substrate (not shown), for example. Due to thecollaboration of the magnetic sensor chips 2 and 3, geomagnetic factorslying in directions A, B, C, and D are detected so as to producedetection signals, which are supplied to a calculation unit (not shown)attached onto the substrate via the leads 6 and the connection leads 7.The calculation unit performs calculations based on detection signals,so that the portable terminal device displays a geomagnetic bearing on adisplay panel (not shown).

As portable terminal devices have been reduced in dimensions, it isstrongly demanded that physical quantity sensors be reduced in size. Thepresent embodiment can easily reduce the overall size of the magneticsensor 1 compared with conventional ones.

That is, the magnetic sensor 1 of the present embodiment ischaracterized in that, as shown in FIG. 3, the side surfaces 13 c of theexterior mold package 13 are each inclined by the angle θ₂ that is setto 5° and are formed in proximity to the outer ends 19 of the magneticsensor chips 2 and 3. Herein, the lower ends of the bottom 13 a projectoutwardly from the outer ends 19 of the magnetic sensor chips 2 and 3 inthe length direction W by the following dimension d, which may beapproximately 0.0166 mm.$d = {0.2 \times \frac{\sin\quad 75^{{^\circ}}}{\tan\quad 85^{{^\circ}}}}$

As described above, it is possible to minimize the dimension d by whichthe lower ends of the bottom 13 a project outwardly. As a result, it ispossible to reduce the overall area of the bottom 13 a of the exteriormold package 13.

In short, the magnetic sensor 1 of the present embodiment is designedsuch that the side surfaces 13 c of the exterior mold package 13 areeach inclined by the angle θ₂ which is set to 5° and are formed inproximity to the outer ends 19 of the magnetic sensor chips 2 and 3;hence, it is possible to reduce the overall area of the bottom 13 a;thus, it is possible to easily downsize the magnetic sensor 1 with asimple structure.

In addition, the leads 6 are arranged to partially overlap with themagnetic sensor chips 2 and 3 in the thickness direction H; hence, it ispossible to further reduce the dimension d by which the lower ends ofthe bottom 13 a project outwardly; thus, it is possible to furtherreduce the size of the magnetic sensor 1.

Furthermore, due to the provision of the inclination portions 15 of theleads 6 by which the magnetic sensor chips 2 and 3 are arranged on thesurfaces 15 a, it is possible to easily incline the magnetic sensorchips 2 and 3 with respect to the bottom 13 a of the exterior moldpackage 13.

As the side surfaces 13 c are broadened outwardly, it is possible toincrease the inclination angles of the magnetic sensor chips 2 and 3while a reduction is secured with respect to the overall area of thebottom 13 a; hence, it is possible to increase the angle θ₁ between theA-B plane and the C-D plane; thus, it is possible to improve thesensitivity of the magnetic sensor 1 for detecting geomagnetism.

In the present embodiment, the angle θ₂ for inclining the side surfaces13 c is set to 5°, which is not a restriction. That is, it is requiredthat the angle θ₂ ranges from 0° to 5°. In addition, dimensions of themagnetic sensor 1 can be appropriately changed.

The present embodiment can be modified in various ways, which will bedescribed below.

(1) First Modification

FIGS. 8 and 9 show a first modification of the present embodiment,wherein parts identical to those shown in FIGS. 1 to 7 are designated bythe same reference numerals; hence, the detailed description thereofwill be omitted.

The first modification is basically similar to the present embodiment,so that the following description will be given with respect todifferences therebetween.

In the first modification, as shown in FIG. 8, the projections 17 thatproject from the lower surfaces of the stages 10 and 11 are eachelongated in a direction perpendicular to the length direction W, sothat they are formed like plates whose widths substantially match thewidths of the stages 10 and 11.

In addition, a plurality of interconnection portions 30 are additionallyformed to establish interconnection between the connection leads 7 andthe stages 10 and 11. The interconnection portions 30 are arrangedopposite to each other at both ends of bases of the stages 10 and 11.Cutouts are formed on side areas of the interconnection portions 30 soas to form twisting portions 31 whose thickness is reduced compared withother portions of the connection leads 7. The twisting portions 31 canbe easily deformed compared with the projections 17. Therefore, theprojections 17 are subjected to pressing by metal molds so that thetwisting portions 31 become deformed; hence, as shown in FIG. 9, it ispossible to establish inclined states with respect to the stages 10 and11.

As the projections 17 are formed like elongated plates, it is possibleto secure satisfactory rigidity therefor; hence, it is possible toeasily incline the stages 10 and 11. In addition, it is possible toreliably secure inclined states of the stages 10 and 11 in a stablemanner.

Incidentally, the first modification is designed such that the leads 6are not integrally formed together with the stages 10 and 11, whereinthe leads 6 lying along both ends of the length direction W areelectrically connected to the bonding pads 5 of the magnetic sensorchips 2 and 3, while other leads, i.e., the connection leads 7 arearranged to encompass the stages 10 and 11 irrespective of the leads 6.

(2) Second Modification

FIGS. 10 and 11 show a second modification of the present embodiment,wherein the second modification is basically similar to the presentembodiment; hence, the following description will be given with respectto differences therebetween.

In the second modification, as shown in FIG. 10, an R-shape portion 32having a smooth round shape is formed at a tip end 17 b of a backside 17a of the projection 17. The R-shape portion 32 is formed as follows:

When the aforementioned lead frame 22 is formed in a punching step inwhich the projection 17 is fixed in position by a die 33 (see FIG. 11),punching is performed using a punch 34 with respect to the projection 17in a direction from the backside 17 a to the surface 17 c, wherein thetip end 17 b of the projection 17 is deformed at edges thereof, thusforming the R-shape portion 32.

Of course, the tip end 17 b is not necessarily formed by punching. Thatis, it is possible to introduce any measures that realize the formationof a round shape at the tip end 17 b of the projection 17.

The second modification can demonstrate prescribed effects similar tothose of the first modification. In addition, as the R-shape portion 32is brought into contact with the interior wall of the metal mold thatpresses the projection 17, it is possible to prevent the metal mold frombeing damaged; hence, it is possible to improve the durability of themetal mold. Generally, a prescribed sheet is arranged on the interiorwall of the metal mold in order to realize easy separation of a productfrom the metal mold. The second modification is advantageous in that asthe R-shape portion 32 is brought into contact with the sheet, it ispossible to reliably prevent the sheet from being damaged by the tip end17 b of the projection 17, which may be conventionally cut into thesheet.

(3) Third Modification

FIGS. 12 and 13 show a third modification of the present embodiment,wherein the third modification is basically similar to the presentembodiment; hence, the following description will be given with respectto differences therebetween.

In the third modification, as shown in FIG. 12, the tip end 17 b of theprojection 17 is extended across the overall length thereof in thelength direction W so as to form an extended portion 35, which isintegrally formed together with the tip end 17 b of the projection 17.

The extended portion 35 is formed by bending the tip end 17 b of theprojection 17. It is preferable that, as shown in FIG. 13, bending beperformed using metal molds simultaneously with the inclination of thestages 10 and 11.

The third modification can demonstrate prescribed effects similar tothose of the second modification. In addition, as a depression appliedto the projection 17 in metal molds is received by the extended portion35, it is possible to easily incline the stages 10 and 11; hence, it ispossible to reliably secure inclined states of the stages 10 and 11 in astable manner.

In the bending of the projection 17, it is possible to additionallyperform press working or photo-etching on the surface and backside ofthe extended portion 35, which is thus reduced in thickness comparedwith other portions as shown in FIG. 14. This realizes easy bending ofthe extended portion 35.

(4) Fourth Modification

FIG. 15 shows a fourth modification of the present embodiment, whereinparts identical to those shown in FIGS. 1 to 7 are designated by thesame reference numerals; hence, the detailed description thereof will beomitted.

The fourth modification is basically similar to the present embodiment,wherein the following description will be given with respect todifferences therebetween.

In short, a magnetic sensor 1 according to the fourth modification ischaracterized in that the side surfaces 13 c of the exterior moldpackage 13 are not inclined; that is, the angle θ₂ is set to zero.

Similar to the present embodiment, a manufacturing method of the fourthmodification includes a bonding step, a connection step, a fixing step,and a molding step. In addition, the fourth modification additionallyintroduces a dicing step in which the lead frame 22 and the exteriormold package 13 are subjected to dicing such that the inclination angleof the side surfaces 13 c of the exterior mold package 13 is forced tobe zero in the thickness direction H, hence, the side surfaces 13 c areformed close to the outer ends 19 of the magnetic sensor chips 2 and 3.

This manufacturing method is a so-called MAP method, in which similar tothe present embodiment, a series of steps (including the bonding stepand molding step described above) are performed; then, the lead frame 22substantially encapsulated in the exterior mold package 13 is subjectedto cutting using a blade 25, so that the side surfaces 13 c are formedto be perpendicular to the bottom 13 a.

A single pair of the magnetic sensor chips 2 and 3 can be necessarilysubjected to a molding step at once. In the fourth modification, thereis provided one sheet of a large lead frame including plural pairs ofmagnetic sensor chips, all of which are simultaneously subjected tomolding, so that the blade 25 is used to isolate individual units ofmagnetic sensors.

As the side surfaces 13 c of the exterior mold package 13 are notinclined so that the inclination angle thereof is set to zero, it ispossible to further reduce the overall area of the bottom 13 a of theexterior mold package 13; hence, it is possible to further reduce thesize of the magnetic sensor 1.

(5) Fifth Modification

FIG. 16 shows a fifth modification of the present embodiment, whereinparts identical to those shown in FIG. 15 are designated by the samereference numerals; hence, the detailed description thereof will beomitted.

The fifth modification is basically similar to the fourth modification,wherein the following description will be given with respect todifference therebetween.

The fifth modification does not use the foregoing dicing step butperforms cutting on a lead frame 22, which is fixed in metal molds, inaccordance with a through-gate method.

In the through-gate method, metal molds provide cavities that are usedto form a plurality of chips and that are connected via runner gates 27.Cavities close to pods are sequentially filled with a resin, so that aresin introduced into one cavity is supplied to a next cavity via therunner gate 27. After completion of the molding step, a cutting metalmold is used to cut the lead frame 22 into individual units of magneticsensors 1, which are then extracted. Thus, it is possible tosimultaneously produce a plurality of magnetic sensors 1.

The fifth modification can demonstrate prescribed effects similar tothose of the fourth modification.

The present embodiment and its modifications are all related to magneticsensors, which is not a restriction. Hence, they can be applied tovarious types of physical quantity sensors such as acceleration sensors.

In addition, it is possible to create further modifications within thescope of the present invention with regard to the first embodiment. Forexample, when chips are further reduced in size, it is possible toincrease the aforementioned inclination angle, which originally rangesfrom 0° to 5° but which can range from 10° to 20°. Even when theinclination angle is increased by use of chips of smaller sizes, it ispossible to demonstrate the same effects as described in conjunctionwith the first embodiment and its modifications.

2. Second Embodiment

The second embodiment of the present invention is related to amanufacturing method of a physical quantity sensor, namely, athree-dimensional magnetic sensor for measuring geomagnetism, which willbe described below.

First, the overall structure of a magnetic sensor produced by themanufacturing method of the second embodiment will be described withreference to FIGS. 19 to 23.

That is, a magnetic sensor 201 shown in FIG. 19 includes two stages 202that are mutually inclined, two magnetic sensor chips 203 that aremounted on surfaces 202 a of the stages 202 so as to measure themagnitude and direction of an external magnetic field, a plurality ofleads 205 that are electrically connected to the magnetic sensor chips203 via wires 204, and an exterior mold package (or a resin moldpackage) 207. Side walls 207 a of the exterior mold package 207 standvertically on a bottom 207 b.

The magnetic sensor 201 is produced using a lead frame 210 including thestages 202 and the leads 205 as shown in FIG. 20.

Next, the details of the lead frame 210 will be described. The leadframe 210 is formed through press working and/or etching performed on athin metal plate 214 such as a copper plate shown in FIG. 21. In thepresent embodiment, a plurality of lead frames 210 are extracted fromone sheet of the thin metal plate 214. Of course, it is possible toappropriately change the number of lead frames and forming positions oflead frames in the thin metal plate 214.

As shown in FIG. 20, the lead frame 210 includes two stages 202 eachhaving a rectangular shape in plan view, a frame portion 211 having aplurality of leads 205 encompassing the stages 202, and a plurality ofinterconnection portions 212, which interconnect the prescribed leads205 and the stages 202 and which are formed at both ends of bases 202 bof the stages 202, which are arranged opposite to each other.

As shown in FIG. 21, the frame portion 211 as a whole corresponds to thethin metal plate 214 having a rectangular shape in plan view so as toencompass a plurality of lead frames 210 therein. Specifically, theframe portion 211 includes intermediate portions 211 a, each of which isformed between the lead frames 210 in proximity to the stages 202, andouter peripheral portions 211 b, which correspond to the outer peripheryof the thin metal plate 214.

Some leads 205 within the leads 205 integrally formed with the frameportion 211 serve as hanging leads for fixing the stages 202 to theframe portion 211 as shown in FIG. 20 and are respectively connected tothe stages 202 via the interconnection portions 212.

Within a single lead frame 210, two stages 202 are disposed in alongitudinal direction F of the frame portion 211 such that tip endsthereof (i.e., opposite ends 202 c of the stages 202) are arrangedopposite to each other. Each of the stages 202 has a pair of projections215 that are elongated inwardly from both ends of the tip end 202 cthereof towards the other stages 202 in the longitudinal direction F.The two projections 215 are formed integrally together with each of thestages 202. By bending bases of the projections 215, the projections 215are respectively projected from lower surfaces (or back sides) 202 d ofthe stages 202 and are thus inclined with respect to the stages 202.

Magnetic sensor chips 203 are respectively mounted on upper surfaces 202a of the stages 202 and are each sensitive to two magnetic factors lyingin two directions of an external magnetic field. Within a single leadframe 210 shown in FIG. 20, one magnetic sensor chip 203 is sensitive totwo directions (i.e., directions A and B) that cross at a right angle onthe surface thereof; and the other magnetic sensor 203 is sensitive tothe other two directions (i.e., directions C and D) that cross at aright angle on the surface thereof. Incidentally, the directions A and Care reverse to each other with respect to the perpendicular direction ofthe longitudinal direction F; and the directions B and D are reverse toeach other in parallel with the longitudinal direction F.

Of course, it is possible to modify the present embodiment such that theother magnetic sensor chip 203 has a sensitivity in the direction Donly. Alternatively, the other magnetic sensor chip 203 can be installedin a horizontal manner.

The interconnection portions 212 have twisting portions 220 that arereduced in thickness compared with other portions of the leads 205 dueto the provision of cutouts formed in both sides thereof. The twistingportions 220 are easy to be deformed compared with the projections.Thus, when the projections 215 are pressed upwardly in a direction fromthe lower surface 202 d to the upper surface 202 a of the stage 202, thetwisting portions 220 are twisted, so that the stage 202 rotates aboutan axial line L passing through the twisting portions 220.

Next, a manufacturing method of the magnetic sensor 201 using theaforementioned lead frame 210 will be described in detail.

As shown in FIG. 21, a single sheet of the thin metal plate 214 issubjected to press working and/or etching so as to form a plurality oflead frames 210 in a frame forming step.

In a bonding step, the magnetic sensor chips 203 are respectively bondedonto upper surfaces 202 a of the stages 202. In this step, the magneticsensor chips 203 are controlled in such a way that sensing directionsthereof are aligned as shown in FIG. 20.

Next, the leads 205 are connected to bonding pads 209 of the magneticsensor chips 203 via the wires 204 in a connection step. Thus, it ispossible to electrically connect the magnetic sensor chips 203 and theleads 205 together. When the stages 202 are inclined, variations mayoccur with respect to bonding areas between the magnetic sensor chips203 and the wires 204 and with respect to bonding areas between theleads 205 and the wires 204. Hence, it is preferable that the wires 204be composed of materials having a bending ability and flexibility.

Next, as shown in FIG. 23, the thin metal plate 214 that is completed inthe connection step is installed in the equipment and is placed at aprescribed position on a base 217 in an installation step. The base 217has a planar surface 218 on which the thin metal plate 214 is placed. Inaddition, the base 217 has a plurality of absorption holes 222 that arearranged in conformity with the intermediate portions 211 a of the frameportion 211. One end of each of the absorption holes 222 is opened onthe planar surface 218, and the other end is each connected withabsorption devices 223.

As described above, the thin metal plate 214 is mounted at theprescribed position on the planar surface 218 of the base 217. Then, theouter peripheral portions 211 b of the frame portion 211 are pressed andclosely attached to the planar surface 218 of the base 217 using a clamp225 having a frame-like shape whose size substantially matches therectangular area defined by the outer peripheral portions 211 b of theframe portion 211. As the outer peripheral portions 211 b of the frameportion 211 are subjected to pressing using the clamp 225, theprojections 215 of the stages 202, which are arranged close to the outerperipheral portions 211 b, are pressed upwardly by the planar surface218. Thus, the opposite ends 202 c of the stages 202 are lifted up whilethe twisting portions 220 are being twisted, wherein the stages 202mutually rotate about axial lines L. The stages 202 are inclined withrespect to the frame portion 211. In contrast, the stages 202 that arearranged in the center area of the thin metal plate 214 are supported bythe projections 215 in such a way that they are floating above theplanar plane 218 because the intermediate portions 211 a arrangedthereby are not subjected to pressing and are thus free. This makes itpossible for the thin metal plate 214 to be fixed in position such thatthe intermediate portions 211 a are placed just above the absorptionholes 222. Incidentally, internal walls of the clamp 225 are verticallyextended with respect to the planar surface 218.

After completion of the installation step, the absorption devices 223are driven so that lower surfaces 227 of the intermediate portions 211 a(corresponding to the lower surface of the frame portion 211) aresubjected to absorption by the absorption holes 222. This producespressure differences in the absorption holes 222, so that theintermediate portions 211 a positioned just above the absorption holes222 are absorbed by the absorption devices 223. For this reason, theintermediate portions 211 a are forced to move downward and are closelyattached onto the planar plane 218. Thus, the entire area of the thinmetal plate 214 is brought into contact with the planar surface 218. Inthis case, the projections 215 are pressed upwardly by the planarsurface 218, so that the opposite ends 202 c of the stages 202, whichare originally floating above the planar surface 218, are lifted upwhile the twisting portions 220 are being twisted; hence, the stages 202mutually rotate about the axial lines L. As a result, all the stages 202are inclined with respect to the frame portion 211 in an inclinationstep.

Other steps subsequent to the inclination step are realized in aso-called MAP method. That is, a resin is introduced into a mold space231 defined by the internal walls of the clamp 225 and the planarsurface 218; then, it is maintained for a prescribed time period; thus,as shown in FIG. 25, it is possible to form an exterior mold package 207sealing the stages 202, magnetic sensor chips 203, and leads 205 in amolding step, wherein the magnetic sensor chips 203 are mutuallyinclined and are fixed inside of the exterior mold package 207. It ispreferable that the resin be composed of materials having a highflexibility in order to prevent inclination angles of the stages 202 andmagnetic sensor chips 203 from being unexpectedly varied. Aftercompletion of the formation of the exterior mold package 207, the clamp225 is removed; thus, as shown in FIG. 16, side walls 207 a of theexterior mold package 207 are vertically extended from a bottom 207 b.

After the removal of the clamp 225, the exterior mold package 207 andthe frame portion 211 are subjected to cutting using a blade so as toisolate individual units of lead frames 210 in a dicing step. Thus, itis possible to produce the magnetic sensor 201 having the lead frame 210in which the side walls 207 a of the exterior mold package 207 arevertically extended from the bottom 207 b.

In the aforementioned manufacturing method, as the lower surfaces 227 ofthe intermediate portions 211 a are subjected to absorption, it isunnecessary to use metal molds for sandwiching the lead frame 210,wherein it is possible to easily incline the stages 202. This reducesthe space required for manufacturing; and it is possible to easilyproduce the magnetic sensor 201 in a short period of time.

The conventionally-known technology may use a pair of upper and lowermetal molds that hold a lead frame vertically so as to incline stages,wherein it may be difficult to adopt the aforementioned MAP method. Theupper and lower metal molds may require extraction slopes allowingexterior mold packages to be extracted therefrom. This forms alimitation in reducing the overall area of the bottom 207 b of theexterior mold package 207. In contrast, as the present embodiment caneasily incline the stages 202 without using the upper and lower metalmolds, it is possible to adopt the MAP method, which may eliminate thenecessity of forming extraction slopes. Therefore, it is possible toreduce the overall area of the bottom 207 b of the exterior mold package207; and it is possible to easily realize downsizing of the magneticsensor 201.

By using the magnetic sensor chips 203 for detecting geomagneticfactors, it is possible to calculate vectors representing thegeomagnetic direction in a three-dimensional space; hence, thegeomagnetic bearing can be displayed on a display panel of a portableterminal device (not shown) incorporating the magnetic sensor 201. Thismakes it possible to additionally provide various navigation functionsusing geomagnetism with portable terminal devices.

In the present embodiment, a pair of the projections 215 are formed atboth ends of the opposite ends 202 c of the stage 202, which is not arestriction. Of course, it is possible to appropriately change thenumber of projections and forming positions of projections in relationto stages.

The magnetic sensor chip 203 is mounted on the upper surface 202 a ofthe stage 202, which is not a restriction. That is, the magnetic sensorchip 203 can be attached to the lower surface of a back side 202 d ofthe stage 202. This makes it easy to electrically connect the leads 205to the magnetic sensor chip 203 without causing interference between theprojections 215 and the wires 204.

The present embodiment uses the absorption holes 222 and absorptiondevices 223, which is not a restriction. That is, it is possible to useother absorption means having appropriate structures. For example, it ispossible to use magnetic force (or magnetic attraction) realized bymagnets, which are attached to the base 217. Herein, it is possible touse permanent magnets or electromagnets. Electromagnets may beadvantageous because it is possible to easily adjust the absorptiontiming and absorption force; in addition, they make it easy to removethe lead frame 210 and magnetic sensor 201 from the base 217 by breakingelectrification therefor.

In the inclination step, the intermediate portions 211 a are closelyattached to the planar surface 218, which is not a restriction. That is,the intermediate portions 211 a can be maintained in a floating stateabove the planar surface 218.

It is possible to appropriately change the design and shape of the leadframe 210. For example, the lead frame 210 can be modified as shown inFIG. 26 in which the foregoing projections 215 are eliminated but astage interconnection portion 240 is provided so as to integrallyinterconnect the stages 202 together. In addition, slits 241 eachelongated in a direction perpendicular to the longitudinal direction Fare formed at both sides of the stage interconnection portion 240. Theslits 241 can be replaced with thinned portions whose thickness isreduced compared with other portions of the stage interconnectionportion 240. Furthermore, lead inclination portions 242, which areinclined upwardly, are formed in the prescribed leads 205 that areconnected to the stages via the interconnection portions 212, whereinthe stages 202 are each positioned upwardly with prescribed offsetvalues.

The aforementioned lead frame 210 is placed at a prescribed position ofa lower mold 246 as shown in FIG. 27, wherein it is sandwiched betweenthe lower mold 46 and an upper mold 45; then, the absorption device 223is driven so as to absorb the stage interconnection portion 240 formedin proximity to the stages 202. That is, the opposite ends 202 c of thestages 202 are lowered so that the stages 202 are correspondinglyinclined. Due to the absorption effected on the stage interconnectionportion 240, the opposite ends 202 c of the stages 202 are rotatablybent about axial lines running through the slits 241, so that the stages202 are gradually inclined while the bases of the lead inclinationportions 240 and the twisting portions 220 are bent; hence, the stageinterconnection portion 240 is closely attached onto the planar plane218. Thereafter, molding is performed by introducing a resin into acavity between the upper mold 45 and the lower mold 46, which hold thelead frame 210 therebetween such that the stage interconnection portion240 is closely attached onto the planar surface 218.

As described above, even though the upper mold 45 and the lower mold 46are used, it is unnecessary to press selected positions of the leadframe 210 during the inclination step of the stages 202. That is, it ispossible to reliably prevent the upper mold 45 and the lower mold 46from being damaged; hence, it is possible to improve the durability ofthe upper mold 45 and the lower mold 46.

Of course, the magnetic sensor 201 can be reliably produced by way ofthe aforementioned MAP method without using the upper mold 45 and thelower mold 46.

The present embodiment can be further modified in various ways, whichwill be described below.

(1) First Modification

FIGS. 28 and 29 show essential parts of the thin metal plate 214realizing the lead frame 210 in accordance with a first modification ofthe present embodiment, wherein parts identical to those shown in FIGS.19 to 25 are designated by the same reference numerals; hence, thedetailed description thereof will be omitted.

The first modification is basically similar to the present embodiment interms of steps in manufacturing, wherein the following description willbe given with respect to differences therebetween.

That is, the bases 202 b of the stages 202 are interconnected to upperends of support walls 229 that vertically stand on the base 217, wherebythe lead frame 210 is positionally lifted up with prescribed offsetvalues. Such a lead frame 210 is formed in the thin metal plate 214 in aframe forming step.

In addition, the absorption device 213 is connected with the absorptionholes 222 having openings, which are equipped with covers 235. Thecovers 235 are hinged to the openings of the absorption holes 222 andare rotatably supported by hinges so as to open and close the openingsof the absorption holes 222. Specifically, the free end of the cover 235moves between a close position at which it closes the opening of theabsorption hole 222 and an open position at which it is retracted insideof the absorption hole 222 so as to realize the opening of theabsorption hole 222. Each of the covers 235 is normally positioned atthe close position by being pressed by an elastic member (not shown).The aforementioned absorption holes 222 are arranged to positionallymatch the opposite ends 202 c of the stages 202. When the thin metalplate 214 is placed at a prescribed position of the base 217, theabsorption holes 222 are arranged opposite to the opposite ends 202 c ofthe stages 202 respectively.

After completion of the installation step that is described in theaforementioned embodiment, the absorption device 223 is driven so as toproduce an absorption force, by which the covers 235 are each forced tomove to the open position irrespective of the operation of the elasticmembers therefor, whereby the absorption holes 222 are opened so as toattract the lower surfaces 202 d of the stages 202 thereby.

In the above, due to pressure differences occurring in the absorptionholes 222, as shown in FIG. 29, the opposite ends 202 c of the stages202 are subjected to absorption via the absorption holes 222 by means ofthe absorption device 223, wherein the stages 202 mutually rotate aboutaxial lines L so that the opposite ends 202 c are gradually loweredwhile the twisting portions 220 are being twisted. As a result, all thestages 202 included in the thin metal plate 214 are inclined withrespect to the frame portion 211, thus completing an inclination step.

Thereafter, similar to the aforementioned embodiment, a molding step anda dicing step are performed, thus producing a magnetic sensor 201 havingthe lead frame 210 of the first modification of the present embodiment.

As described above, it is possible to reliably incline the stages 202with a simple structure.

(2) Second Modification

FIGS. 30 and 31 show essential parts of the lead frame 210 in accordancewith a second modification of the present embodiment, wherein partsidentical to those shown in FIGS. 19 to 25 are designated by the samereference numerals; hence, the detailed description thereof will beomitted.

In the second modification, the leads 205 are each bent in an L-shapeand partially project upwardly from the frame portion 211. Upper ends ofthe leads 205 are respectively connected to the bases 202 b of thestages 202 via interconnection portions 212, which are each elongated ina longitudinal direction F. Thus, the stages 202 are each lifted upabove the frame portion 211 with prescribed offset values.

The aforementioned lead frame 210 is formed in a frame forming step;then, the aforementioned steps are performed so as to produce a magneticsensor 201 having the lead frame 210 of the second modification.

The second modification can demonstrate prescribed effects similar tothose of the aforementioned embodiments. In addition, the secondmodification is advantageous in that the upper surfaces of the magneticsensor chips 203 substantially match the surfaces of the leads 205 inheight. This makes it easy to electrically connect the leads 205 to themagnetic sensor chips 203. Furthermore, the second modification canreduce the lengths of the wires 204 and can also reduce variations ofthe wires 204 during the inclination of the magnetic sensor chips 203.Thus, it is possible to improve the reliability in producing themagnetic sensor 201.

(3) Third Modification

FIGS. 32 to 34 show essential parts of the lead frame 210 in accordancewith a third modification of the present embodiment, wherein partsidentical to those shown in FIGS. 19 to 25 are designated by the samereference numerals; hence, the detailed description thereof will beomitted.

In the third modification, as shown in FIGS. 32 and 33, inclinationportions 233 are formed at the bases 202 b of the stages 202 and areextended outwardly in a slanted manner towards the upper surfaces 202 aof the stages 202. The lead frame 210 having the inclination portions233 is formed in a frame forming step.

In the above, the absorption holes 222 of the base 217 are arranged topositionally match the inclination portions 233. When the thin metalplate 214 realizing the lead frame 210 shown in FIG. 32 is placed at aprescribed position of the base 217, the inclination portions 233 of thelead frame 210 are arranged opposite to the absorption holes 222 on thebase 217.

Similar to the aforementioned embodiment, after completion of aninstallation step, when the absorption devices 223 are driven, lowersurfaces 233 a of the inclination portions 233 are subjected toabsorption via the absorption holes 222. That is, as shown in FIG. 34,as the inclination portions 233 are absorbed by the absorption holes222, the stages 202 mutually rotate so that the opposite ends 202 c aregradually lowered while the twisting portions 220 are being twisted.When the inclination portions 233 are closely attached onto the planarplane 218, they are arranged substantially in the same plane as theframe portion 211. Thus, all the stages 202 included in the thin metalplate 214 are inclined with respect to the frame portion 211 as theopposite ends 202 c are lifted up, thus realizing an inclination step.

Thereafter, the aforementioned molding step and dicing step areperformed so as to produce a magnetic sensor 201 having the lead frame210 shown in FIG. 32.

Thus, it is possible to reliably incline the stages 202 with a simplestructure.

Incidentally, the second embodiment and its modifications are alldescribed in relation to the MAP method, which is not a restriction.That is, the lead frame 210 can be subjected to molding using upper andlower molds.

In addition, the second embodiment and its modifications are alldescribed in connection with the magnetic sensor 201, which is not arestriction. That is, they can be easily adapted to other types ofphysical quantity sensors such as acceleration sensors.

3. Third Embodiment

Next, a manufacturing method for a physical quantity sensor according toa third embodiment of the present invention will be described. The thirdembodiment is basically similar to the second embodiment, which isdescribed in conjunction with FIGS. 19 to 34; hence, the detaileddescription thereof will be omitted.

The magnetic sensor 201 according to the third embodiment ismanufactured without using metal molds, wherein after completion of theconnection step, the thin metal plate 214 is fixed at a prescribedposition on the base 217, so that as shown in FIG. 35 (which basicallycorresponds to FIG. 27), the stage interconnection portion 240 ispositioned oppositely to the absorption hole 222 in aninstallation-fixation step. Then, the absorption device 223 is driven soas to absorb the stage interconnection portion 240 formed in proximityto the stages 202, which are thus gradually inclined as the oppositeends 202 c are lowered, thus realizing an inclination step.Specifically, when the stage interconnection portion 240 is subjected toabsorption, the opposite ends 202 c of the stages 202 are respectivelybent about axial lines running through the slits 241, wherein the stages202 are inclined as the bases of the lead inclination portions 242 andthe twisting portions 220 are being bent, so that the stageinterconnection portion 240 is brought into close contact with theplanar surface 218. In such a close contact state, a resin is introducedso as to mold an exterior mold package in a molding step. Thus, similarto the second embodiment, it is possible to produce the magnetic sensor201 in accordance with the third embodiment, which is advantageousbecause the stages 202 can be reliably and speedily inclined.

FIGS. 36 and 37 show a modification of the magnetic sensor 201, whereinparts identical to those used in the second embodiment are designated bythe same reference numerals; hence, the detailed description thereofwill be omitted.

In the installation-fixation step, the thin metal plate 214 is fixedonto the base 217; then, it is subjected to pressing by means of aplurality of pressing pins 246 in a direction perpendicular to theplanar surface 218.

Each of the pressing pins 246 is elongated in a columnar manner. Thepressing pins 246 are supported by a support frame 245 having arectangular lattice-like shape. When the support frame 245 from whichthe pressing pins 246 project downwardly is placed above the base 217,the pressing pins 246 are positioned opposite to intersecting pointsbetween the intermediate portions 211 a, which are formed in a matrixform on the thin metal plate 214.

Specifically, after the thin metal plate 214 is fixed onto the base 217in the installation-fixation step, the support frame 245 is moved abovethe thin metal plate 214 such that the pressing pins 246 are eachpositioned precisely above the intersecting points between theintermediate portions 211 a; then, the support frame 245 is moveddownwardly towards the base 217. At the prescribed timing, the tip endsof the pressing pins 246 are brought into contact with the intersectingpoints between the intermediate portions 211 a, which are thus presseddownwardly. By further moving down the support frame 245, theintermediate portions 211 a are lowered in position towards the planarsurface 218. Thus, as shown in FIG. 37, the stages 202 mutually rotateabout the axial lines L as the opposite ends 202 c thereof are slightlylifted up while the twisting portions 220 are being twisted. When thesupport frame 245 is fixed at a prescribed position in connection withthe clamp 225, the intermediate portions 211 a are brought into closecontact with the planar surface 218, so that the stages 202 are inclinedwith respect to the frame portion 211, thus realizing an inclinationstep.

In such an inclined state, a resin is introduced into the space, whichis defined by the base 217, clamp 225, and support frame 245, so as tomold an exterior mold package in a molding step. Thereafter, the supportframe 245 is removed. Thus, similar to the second embodiment, a dicingstep is performed so as to produce the magnetic sensor 201 in accordancewith the third embodiment.

In the above, the stages 202 can be reliably and speedily inclined byuse of a simple structure for manufacturing.

Incidentally, the support frame 245 is not necessarily formed in arectangular lattice-like shape. For example, it can be formed like aflat plate. That is, the support frame 245 can be appropriately changedin shape and size.

The third embodiment uses the pressing pins 246 that press theintersecting points between the intermediate portions 211 a, which isnot a restriction. That is, it is possible to use appropriately designedpressing means; and it is possible to change pressed positions of thethin metal plate 214. For example, pressing is performed at prescribedpositions which are disposed along the whole lengths of the intermediateportions 211 a with prescribed distances therebetween.

Of course, the third embodiment is not necessarily limited to themagnetic sensor 201; hence, it can be applied to other types of physicalquantity sensors such as acceleration sensors.

Lastly, the present invention is not necessarily limited to theaforementioned embodiments, hence, it is possible to realize variousdesign changes and modifications within the scope of the inventiondefined by the appended claims.

1. A manufacturing method for a physical quantity sensor in which a pairof physical quantity sensor chips are incorporated into an exterior moldpackage, which is molded using a resin, each of the physical quantitysensor chips being inclined with respect to a bottom of the exteriormold package, said manufacturing method comprising: bonding the physicalquantity sensor chips onto stages of a lead frame, which is formed byprocessing a thin metal plate; establishing an electric connectionbetween the lead frame and the physical quantity sensor chips; fixingthe lead frame equipped with the physical quantity sensor chips in acavity of a metal mold; and injecting a resin into the cavity of themetal mold holding the lead frame and the physical quantity sensorchips, thus forming the exterior mold package, wherein side surfaces ofthe exterior mold package are each inclined in a thickness direction byan angle, which ranges from 0° to 5°, and are formed in proximity toouter ends of the physical quantity sensor chips.
 2. The manufacturingmethod for a physical quantity sensor according to claim 1, wherein theangle is set to zero, so that the lead frame and the exterior moldpackage are subjected to dicing so that the side surfaces of theexterior mold package are formed in proximity to the outer ends of thephysical quantity sensor chips.
 3. A manufacturing method for a physicalquantity sensor, comprising: forming a lead frame having a plurality ofstages, a frame portion having a plurality of leads that are formed toencompass the stages, and a plurality of interconnection portions forinterconnecting prescribed ends of the stages to the frame portion;bonding a plurality of physical quantity sensor chips onto the stages ofthe lead frame; electrically connecting the leads to the physicalquantity sensor chips; placing the lead frame onto a planar surface of abase; and absorbing prescribed portions related to the stages of thelead frame onto the base, wherein due to absorption, the stages mutuallyrotate about axial lines while the interconnection portions are beingbent, so that the stages are inclined with respect to the frame portion.4. The manufacturing method for a physical quantity sensor according toclaim 3, wherein the prescribed portions correspond to intermediateportions formed between the stages and are subjected to absorption byway of absorption holes connected with absorption devices in the base.5. The manufacturing method for a physical quantity sensor according toclaim 3 further comprising: fixing a periphery of a thin metal platehaving the frame portion encompassing a plurality of lead frames bymeans of a clamp that vertically stands on the planar plane of the base;injecting a resin into a space holding the thin metal plate, which isdefined by the planar plane and the clamp, so as to simultaneously moldexterior mold packages respectively encapsulating the lead frames; andsubjecting the frame portion to dicing so as to isolate individual unitsof the exterior mold packages.
 6. The manufacturing method for aphysical quantity sensor according to claim 3, wherein a plurality ofprojections project downwardly from the stages, so that due toabsorption of the prescribed portions, which match a lower surface ofthe frame portion in proximity to the stages, the projections aresubjected to pressing so that prescribed ends of the stages are pressedupwardly.
 7. The manufacturing method for a physical quantity sensoraccording to claim 3, wherein the stages are lifted upwards from theframe portion with prescribed offset values, so that due to absorptionof the prescribed portions, prescribed ends of the stages are lowereddownwards.
 8. The manufacturing method for a physical quantity sensoraccording to claim 3, wherein a plurality of inclination portions areeach extended upwardly from the stages in a slanted manner, so that theinclination portions are subjected to absorption and are lowered so asto lift up prescribed ends of the stages.
 9. A manufacturing method fora physical quantity sensor using a lead frame that includes a pluralityof stages for mounting physical quantity sensor chips thereon, a frameportion having a plurality of leads encompassing the stages, and aplurality of interconnection portions for interconnecting prescribedends of the stages to the frame portion, said manufacturing methodcomprising: forming a plurality of lead frames in a thin metal plate;bonding the physical quantity sensor chips on the stages in each of thelead frames; electrically connecting the leads to the physical quantitysensor chips; placing the thin metal plate on a planar surface of abase; clamping a periphery of the thin metal plate by use of a clampthat vertically stands on the planar surface of the base; pressingprescribed portions in proximity to the stages in a directionperpendicular to the planar surface so as to incline the stages withrespect to the frame portion while the interconnection portions arebeing bent about axial lines; introducing a resin into a space definedby the clamp and the planar surface of the base so as to mold a packageencapsulating the lead frame in which the stages are mutually inclinedwith respect to each other; and dicing the frame portion and thepackage.
 10. The manufacturing method for a physical quantity sensoraccording to claim 9, wherein pressing pins are used to press theprescribed portions in proximity to the stages in the directionperpendicular to the planar surface so as to incline the stages withrespect to the frame portion.
 11. The manufacturing method for aphysical quantity sensor according to claim 9 further comprising:absorbing the prescribed portions formed in proximity to the stages in adirection towards the planar surface, wherein projections projectingfrom the stages are subjected to pressing by the planar surface due toabsorption, so that opposite ends of the stages are moved oppositely tothe planar surface, thus inclining the stages with respect to eachother.
 12. The manufacturing method for a physical quantity sensoraccording to claim 9 further comprising: absorbing the prescribedportions formed in proximity to the stages in the direction towards theplanar surface, wherein the stages are initially positioned apart fromthe planar surface of the base with prescribed offset values, so thatopposite ends of the stages are moved towards the planar surface due toabsorption, thus inclining the stages with respect to each other. 13.The manufacturing method for a physical quantity sensor according toclaim 9 further comprising the step of: absorbing the prescribedportions formed in proximity to the stages in the direction towards theplanar surface, wherein inclination portions extending from the stagesare inclined due to absorption, thus inclining the stages with respectto each other.
 14. The manufacturing method for a physical quantitysensor according to claim 4, wherein a plurality of projections projectdownwardly from the stages, so that due to absorption of the prescribedportions, which match a lower surface of the frame portion in proximityto the stages, the projections are subjected to pressing so thatprescribed ends of the stages are pressed upwardly.
 15. Themanufacturing method for a physical quantity sensor according to claim5, wherein a plurality of projections project downwardly from thestages, so that due to absorption of the prescribed portions, whichmatch a lower surface of the frame portion in proximity to the stages,the projections are subjected to pressing so that prescribed ends of thestages are pressed upwardly.
 16. The manufacturing method for a physicalquantity sensor according to claim 4, wherein the stages are liftedupwards from the frame portion with prescribed offset values, so thatdue to absorption of the prescribed portions, prescribed ends of thestages are lowered downwards.
 17. The manufacturing method for physicalquantity sensor according to claim 5, wherein the stages are liftedupwards from the frame portion with prescribed offset values, so thatdue to absorption of the prescribed portions, prescribed ends of thestages are lowered downwards.
 18. The manufacturing method for physicalquantity sensor according to claim 4, wherein a plurality of inclinationportions are each extended upwardly from the stages in a slanted manner,so that the inclination portions are subjected to absorption and arelowered so as to lift up prescribed ends of the stages.
 19. Themanufacturing method for a physical quantity sensor according to claim5, wherein a plurality of inclination portions are each extendedupwardly from the stages in a slanted manner, so that the inclinationportions are subjected to absorption and are lowered so as to lift upprescribed ends of the stages.